Halo effect

According to Susan J. Herman, author of Hiring Right, A Practical Guide, the interview is the most frequently used selection tool and the least valid and reliable. Validity is the degree to which a selection tool like testing or interviewing measures what it is supposed to measure. The closer a statistic is to 1, the more valid it is. Yet interviews have an average validity of 0.14 while ability testing has an average validity of 0.53.